When Mark Zuckerberg took the stage at Thursday’s Android-centric event at Facebook headquarters and began by saying that the company was finally announcing a Facebook phone, one thing became clear: he was teasing. Facebook wasn’t announcing a Facebook phone. Or at least it wasn’t announcing the Facebook phone which has been the subject of rumors for years now.

Instead, the company was announcing countless Facebook phones, by introducing Facebook Home, an app which replaces Android’s standard interface with its own homescreen and lock screen, allowing people to make handsets they already own into Facebook-centric phones. It also showed off HTC’s appropriately-named First, the first of what could be many phones with Facebook Home pre-installed as their standard interface.

As usual, I came out of the event with lots of questions. I got to ask a few of them during a post-unveiling chat with Adam Mosseri, Facebook’s director of product for Facebook Home. Herewith, the stuff I’ve been wondering about, with some answers from Mosseri.

1. How long has this been in the works?

Scuttlebutt concerning a Facebook phone dates back to at least 2010. But Mosseri told me that Home has only been in the works for a year or so. It represents an aggregation of several discrete ideas the company had been toying with, such as the Cover Feed and the Chatheads messaging service. It was only in July or August of last year that work began on Home in earnest.

2. Do actual people want people-centric phones?

Zuck spent a fair chunk of his time today declaring that phones should be organized around people and sharing, not apps. It’s a logical stance to take when you’re the CEO of Facebook. But it also gave me a deep sense of deja vu, since I’ve sat through numerous other press conferences in which tech execs said pretty much the same thing. But none of the previous people-centric interfaces — from Motorola’s Motoblur to Windows Phone — have caught on. For now, at least, most people seem quite happy with app-centric phones.

Then again, Facebook Home asks less of its potential users than previous attempts at people-first interfaces: you don’t need to buy a new handset or commit to an immature operating system or give up the apps you like. All you need is an Android phone that’s compatible with Home, and if you don’t like the new interface, you can delete it with a few taps. So if you’re the least bit intrigued, there’s no reason not to give it a try.

Still, with all due respect to Zuckerberg, I don’t think it’s yet clear that the basic concept here is one which resonates. We’ll know Facebook nailed it if the idea suddenly has the widespread appeal that’s eluded it until now.

3. How far will this go?

At the moment, Facebook Home isn’t a full-blown mobile version of Facebook or a rich general-purpose smartphone environment — it’s got only a few features, and hands you off to Facebook’s standard Android app and other programs to handle a lot of stuff. It also lacks support for some otherwise standard Android features, such as homescreen widgets. Facebook released something quickly rather than waiting until it had built everything a typical user might want.

Zuckerberg said that Facebook plans to release meaningful updates to Home every month. If the company follows through, the app will evolve rapidly. A year from now, it might be quite different; at some point, it might not require the standard Facebook app anymore. And if it gets rich enough, featurewise, it could take on Google’s standard Android interface more directly than it currently does.

4. Hey, what about privacy?

I asked Mosseri if Facebook Home introduced any new privacy implications, and he answered at first by talking about how you can lock up your private information on the phone so someone who gets ahold of it can’t see it. I then clarified that I was talking about issues relating specifically to Facebook privacy, and he said that Home respects the Facebook privacy settings you’ve already specified.

That answer probably wouldn’t be enough to pacify GigaOm’s Om Malik, who says that Home destroys any notion of privacy. Om’s worried that Facebook will use Home’s always-on nature to figure out stuff it couldn’t otherwise deduce, such as where users live and whether they’re walking, running or driving. Of course, Facebook Home isn’t the only app which would be technically capable of doing so. But it would be comforting to know that the company isn’t going to do any of these things — at least without explicit permission.

5. And battery life?

Home runs in the background, downloading information from Facebook when you’re not using your phone. That’s how it’s able to display photos and updates so quickly when you are using the app. But background downloads of this sort run the risk of killing your battery. Mosseri told me that Facebook worked very hard to make sure that doesn’t happen: it adjusts the amount of stuff it downloads depending on whether you’re on a wi-fi or cellular connection, and cuts itself off if your battery runs dangerously low.

6. Is the HTC First a Facebook phone?

In the demo room that was part of the event, CBS Radio’s Larry Magid and I were discussing the First, and one of us referred to it as “a Facebook phone.” A nearby Facebook rep, not previously involved in our conversation, spoke up and said, quite firmly, that the First was not a Facebook phone and there was no such thing as a Facebook phone.

It’s all a matter of semantics. The First isn’t being sold by Facebook, and doesn’t have any unique features. But really, it’s consumers who will decide whether it’s a Facebook phone or not. If the only people who buy it turn out to be folks who care about Facebook above all else…well, then, it’ll be a Facebook phone.

7. Is this user interface the future of Facebook?

Until now, Facebook on smartphones has been a somewhat simplified, shrunk-down variant of full-blown browser Facebook. The single most signficant think about Home may be that it’s Facebook’s first real reimagining of what its service should look like on a phone. I’m curious whether it’ll come to be what people think of when they think of mobile Facebook — and whether aspects of its look and feel might even migrate to browser-based Facebook.

8. Where’s the Facebook-centic search?

When an attendee at the event asked Zuckerberg what sort of search was available in Home, Zuck curtly said that it was Android, so it could use Google or anything else you wanted. Maybe today. But isn’t it a no-brainer that a Facebook-centric phone environment should have Facebook’s Graph Search? Wouldn’t it be surprising if Facebook wasn’t working on its own, Facebook-first equivalent of Android’s Google Now and Apple’s Siri?

9. How big a barrier is the hassle of installation?

If you’re reading this article, you’d likely have no problem replacing the standard Android homescreen with Facebook Home. It’s not the world’s most intuitive process though, and I have a sneaking suspicion that the average non-nerd Android user may not even be aware that it’s possible to change Android in such a fundamental way. Will people who might love Home never see it because they’re flummoxed by the installation process?

10. Does this represent a further splintering of Android?

Zuckerberg and his colleagues kept reiterating that Home isn’t an operating system, and that it wouldn’t make sense for Facebook to do something like this by coming up with its own heavily customized version of Android, as Amazon has done for the Kindle Fire and Barnes & Noble has done for the Nook. (Even Samsung seems to be tip-toeing in this direction with the Galaxy S4.)

But if Home is a hit, it’ll have a meaningful impact on the Android ecosystem: millions of people could end up using Android in a form whose look, feel and functionality are determined by Facebook, not Google. The fact that Facebook managed to pull that off without digging deeply into the operating system itself wouldn’t matter much.

11. Will any of this make its way to iOS?

Facebook Home in its current incarnation would be an impossibility on iOS in its current incarnation. Apple’s operating system doesn’t allow a third party such as Facebook to swap in its own replacement for fundamental features such as the home screen, or to integrate with system features such as text messaging. It’s unlikely that Apple would permit Facebook to build an app launcher for iOS, even if it were a conventional app rather than a home-screen replacement. Even the way Chatheads sit on top of other apps would be a no-go on an iPhone.

Still, there’s no reason why a Facebook app for iPhone couldn’t incorporate certain apsects of Home’s look and feel — the Cover Feed photos, for instance, or perhaps a modified version of Chatheads. I asked Mosseri about this possibility, and while he stressed that he’s not responsible for Facebook’s iOS apps, he said “all of our teams talk to each other a lot — so some of the design principles will definitely end up in an iOS product.”

12. Will custom Android environments become a fad?

Until now, third-party Android home-screen and lock-screen apps have been niche products at best, unless you count the ones custom-designed by hardware makers such as Samsung and HTC. If Home starts to matter, will other companies want a piece of the action? Could there be a Twitterphone or a LinkedInphone or an eBayphone? Is the notion that Microsoft might build a home screen for Android, integrated with Outlook.com and SkyDrive, completely nuts?

Whatever happens with Home, it won’t be boring — watching it develop will be way more fun than speculating about a mythical Facebook phone ever was.

Apart from the issues you raise in the article, I can think of a few more that might become apparent once people start using it on different Android phones. One is build quality of the software. I know from experience that LinkedIn have had all manner of problems with their mobile and tablet apps on various devices, particularly older one - the dedicated groups on LinkedIn are ringing with complaints about crashing. I hope for Facebook's sake that they've done a LOT of testing, because if they haven't then the anger that will be coming their way will be phenomenal.

The other issue is more fundamental - will people be willing to live within a walled garden on their phone that is primarily what Facebook gives them? Email is one area where most people depart from Facebook-land back to either the phone's own email app or an alternative client. I know Facebook has given all of their users an (at)Facebook.com email address - in a lot of cases, replacing it as the default shown on their profiles, much to the annoyance of many. But I'm guessing the number of people using Facebook for their email is in very small numbers indeed right now. Another area is that of other social networks - Facebook may have the most users, but a lot of them don't limit themselves to just Facebook. Will Home just pretend that there are no other social networks out there? Finally, games - yes, there are lots of Facebook-linked ones already, but many more that don't need Facebook to function - will Home get in the way of your playing?

An interesting move by Facebook who are now trying to become the hub of your online presence not only on one device, but on all of them (at least the Android ones for now...).

Now, from a privacy point of view this is obviously scary and more clarification is needed.

As Gartner Analyst Carolina Milanesi mentioned “it makes sense for the company to “enable Facebook in the best possible way” on smartphones” rather than creating a whole new device (or an OS).

The main point I think is the fact that Facebook is capitalising on the ever changing role of mobile devices in our life. They are more like lifestyle devices rather than communication devices these days.

I like the look of HTC First but I don't want Facebook home, or anything related to Facebook anywhere near me. Will I be able to truely remove it, and know it isn't tracking me, selling my phone number and other data to its customers. It was bad enough being targeted for adverts on Facebook, but will having this app on my phone make everything stored on the phone available to them?

@boomer_babe Good question, and I'm going to try to find out. From a hardware standpoint, the First is an interesting phone, with a nice minimalist design. I'm glad to see HTC opting out of the screen-size wars, at least for this model.

Finally, FINALLY somebody advised him not to talk like Kristen Stewart!! This is the first time I've seen him talking without those annoying question mark intonations in pretty much every declarative sentences. That just makes anyone to sound plain stupid.